Printing systems such as copiers, printers, facsimile devices or other systems having a print engine for creating visual images, graphics, texts, etc. on a page or other printable medium typically include various media feeding systems for introducing original image media or printable media into the system. Examples include thermal transfer printers. Typically, a thermal transfer printer is a printer which prints on media by melting a coating of ribbon so that it stays glued to the media on which the print is applied. It contrasts with direct thermal printing where no ribbon is present in the process. Typically, thermal transfer printers comprise a supply spindle operable for supplying a media web and ribbon, a print station, and a take up spindle. New ribbon and media is fed from the supply spindle to the print station for printing and then the ribbon is wound up by the take up spindle while the media is exited from the print station. The media feed path typically includes media guide structures provided at predetermined locations operable for registering inserted media by moving one or both of the guides to engage opposite sides of the media, thereby fixing the location of the media relative to the path within the print system.
Conventional approaches for media width registration and identification include manual identification with no sensing means, wherein a user is prompted to input the media size and orientation. Heretofore, conventional approaches yield undesirable results. For instance, conventional approaches fail to provide for automatic adjustments in printhead pressure, ribbon supply and take up tension and rewinder tension due to variances in the media width. Further, conventional approaches fail to provide the printer with an ability to compare the width of the image to be printed with the actual media width. Such failures oftentimes lead to off center image printing, printing defects or printer failure. Indeed, should the media width not be accommodated for, wax (ink) may be undesirably deposited on the platen roller or firing elements on the printhead in free space may occur. One skilled in the art will appreciate that firing elements in free space may cause the elements to overheat and burn out.
Thus, there remains a need for improved media width sensing techniques and apparatus by which an automatic or semi-automatic determination of media width is provided and by which the need for width sensing system calibration can be managed. It would, therefore, be desirable to provide a sensing apparatus or device operable for detecting and determining the media width along a feed path of a printer. By detecting and determining the media width in the printer, automatic adjustments can be made to the printhead pressure, ribbon supply tension, ribbon supply take up, and rewind tension, thereby ensure a higher quality printed image and prolonger printer operation. Further, by detecting and determining the media width in the printer, associated software can compare the width of the image to be printed to the media width and notify the operator that they may be printing off the media.